Patent Literature 1 discloses IPsec (Security Architecture for Internet Protocol) communication devices that perform a communication by establishing a secure path with IPsec. According to Patent Literature 1, when the communication is interrupted, the IPSEC communication devices are switched to an interruption mode so that either device performing the communication can re-establish the path and the time required to re-establish the path can be shortened.
In Patent Literature 1, security association (which will be referred to as SA) is performed as a procedure for securing an agreement about a data exchange method and protection method between devices performing an IPsec communication. A lifetime, a sequence number, and so on are included as parameters in the parameters of such SA of IPsec (see paragraph 0028 in Patent Literature 1). Other than the above IPsec, devices that perform communications by using a tunneling protocol such as GRE (Generic Routing Encapsulation) or GTP (GPRS Tunneling Protocol for User Plane) manage tunnel state information (for example, sequence numbers).
Patent Literature 2 discloses a configuration including: VPN packet transfer devices that transfer user packets via a common network; and a VPN controller that exchanges information about processing for transferring the user packets with nodes such as routers and terminals in user networks by using a user network control protocol such as a routing protocol. In addition, the VPN controller receives settings about packet filtering, traffic control, address conversion, and so on from a user as a system administrator and distributes these items of information to the VPN packet transfer devices.
Patent Literature 3 discloses a node (automatic network construction device) that performs identification information reception processing for receiving identification information on a C-plane from a neighboring node on a D-plane in a GMPLS network and tunnel setting processing for setting a communication tunnel for encapsulating and transmitting/receiving data via a cable connected to this neighboring node.
Non-Patent Literatures 1 and 2 are examples of a centralized-control-type network related to the present invention.
[Patent Literature 1]
    Japanese Patent Kokai Publication No. JP2011-170157A[Patent Literature 2]    Japanese Patent Kokai Publication No. JP2005-057693A[Patent Literature 3]    Japanese Patent Kokai Publication No. JP2013-026743A